I'd like to use a 749 on a LT1.. problem is I don't have a 4 pulse per crank rev signal... anyone know what is suitible?

 

You may have a couple of problems.
By wanting to use the 749 I'm venturing a guess you want to go other then N/A.

The Opti-Spark wastes alot of spark energy in there cap rotor design, ie about an 1/8" gap in there.
The best only cure I know of for that is going to a LS1 coil near plug setup. I believe the Bailey Eng setup to do that gives a regular Distributor Refence Pluse. If the Bailey devise gives a DRP then it should be a bolt together.

 

humm..

Bailey Eng setup

What is that?

The car is supercharged (roots) and is the factory 1 bar speed density.. the roots blower needs alot of AE... you know FMU's really aren't consistant with the tuning either.. I'm hoping a 2 bar or 3 bar speed density swap will make life eaiser

its makeing 9psi with the stock pulley on it.. i want to pulley it up to 15-16 real soon... i nkow the FMU is just going to cause problems too.

 

acutally.. i wonder if i parrellel the stock pcm and a 749 .....

I wonder if the tach signal off my msd box would work????

 

How about backing up to square one with what your trying to do.
What year, LT1?
Have you been editing the pcm your have?.

Your PCM can share the TPS, but the coolant and MAT sensors have to be isolated. At different temps they change pull up resistors in the PCM/ECM and the values may vary.

Do you want the 749 to run just the fuel then?.

The MSD signal may have some timing offsets to it. Hard letting what they might have in the box.

There's been a few LT1 running low boost that haven't pegged the MAF. Some clever tuning just might let you use the MAF and boost.

 

this is a 93 LT1.. No MAF

Yes i've been editing the computer but the thing is blind beyond 1 bar of boost so its hard to get what you need out of it.

Its also got a eaton roots blower which makes boost sorta like a turbocharged car only it snaps to booost alot alot unimaginally faster which makes the AE tough...

The more I think about it the more I think this would work.. I think i'll let the stock PCM control the idle and all emmissions equiment, cruize, fans, tach and speedometer etc. and then use the 749 (or 730 with 749 code and pinned out correctly) for the fuel/spark

the 749 will probally need its own ignition modual, map, temp sensors (water and intake), and i'll just let it use the TPS and o2's.. just turn off the trouble code in the 93 PCM.


I've got the AE, VE, Spark, and PE extremely close right now.. in fact the car will probally would pass as it "could have come from the factory that way" Ie no surging or anything... but the thing just isn't very conisitant with the FMU controlling fuel enrichment delta boost.

I think the only problem might be is that the tach signal from my MSD-6BTM might be different from the usual cam/crank sensor.. does anyone know if the magnetic reluctor wheel is keyed for TDC or anything?

bottom line, I want to get a 2-3 bar speed density system on the car, especially when i pulley up the blower a little. not so sure if Accel DFI would be better or not for a street driven car.

 

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Sorry, can't address your issues, I'm a 730/$58 learner as well, and I just learned some more listening in on what Bruce had to say about the PCM's and the pullup resistors. So free bump anyway.

I plan to use an Eaton (M112) on a 5.0L engine, and I've been reading Corky Bell's "Supercharged". I don't know if you have an intercooler, but an Eaton at 16psi would be producing a huge amount of heat. Have you thought about what to do about this?

John

 

You might reincorpate the stock MAF and do some data logging.

If your not pegging or *just* pegging it, you might be alot easier. With the later high frequency MAFs, they can read alot of air flow, I forget the number off hand, but it's a serious amount. And having the 4" version available should be about 0 in the way of restriction. And if you did a blow thru then at WOT it isn't worth menitonioning as far as restriction goes.

I'd first recommend getting some injectors so you don't have to use an FMU. By the time you get enough rate to really do some good you'll have to add a bunch of fuel pump to have enough capacity at the high PSI's. There's always cheap used injectors around, so getting a first set to get in the neighborhood isn't too expensive.

Might look here at my I/C delete for an idea about using fuel as a cooling agent.

http://home.woh.rr.com/brucesgn/

 

This car doesn't have a stock MAF. It didn't come with a mass air meter from the factory. thats the problem i'm addressing. Its a 1 bar speed density setup from the factory


I'm using water/alcohol for cooling. water alone can absorb 6 times more heat that fuel.